By use of a series of model steroid molecular interaction systems we plan to elucidate the nature of steroid hormone - protein bonding. Amino acids, small peptides and synthetic polypeptides interacting with a series of steroids will be monitored by optical methods and changes in diffusion rates. The aqueous solubility of steroids, and the parameters governing such solubilities, will be measured. Associated with these studies will be an investigation of plasma testosterone - estradiol binding globulins of various species including human and bovine. BIBLIOGRAPHIC REFERENCE: "Circular Dichroism of Bovine Serum Albumin -Testosterone Systems" - R. Tucker and Gene F. Lata, J. Ster. Biochem. 6, 1523 (1975).